Congressional Democrats are poised to wrap up work on their health care bill in early 2010, but the battle over public opinion will persist for years.

The most recent health care polling paints a bleak picture for Democrats as they prepare for a historic vote in the Senate later this week. The national numbers show a growing majority of likely voters oppose their push to expand coverage to millions of uninsured Americans. The numbers are even worse in some critical battlegrounds.

But with support slipping in places like Little Rock, Ark., and Las Vegas, it’s worth asking: Do these people even know what’s in the bill?

The short answer is no. And Democrats hope changing the national conversation from general rhetoric to specific provisions will brighten the national mood.

As the bill changed over time, most Americans’ opinions were shaped less by hard information about actual provisions than by themes in the debate — what role the government should have in the health care industry and whether the legislation would add more red ink to the federal balance sheet.

“What you have is a general impression about whether people or people close to them think things will be better with passage of this bill,” said Robert Blendon, a professor of health policy and political analysis with Harvard’s School of Public Health. “The take-away from the debate to this point is that this bill is not going to help people.”

In fact, more than half of the respondents to most health care polls say they don’t know enough about the bill to have a hard opinion — if they’re given that option, Democratic pollster John Anzalone said in an e-mail.

“What they hear is some notions — some accurate, some distorted — about what Democrats are trying to do,” said Charles Franklin, a polling expert at the University of Wisconsin at Madison.

As the poll numbers slip, Democrats are banking on the fact that they can sell the bill now that lawmakers can point to specific policies embedded in the legislation.

“If you look at the morning polls, there are some polls that show, just as a result of our passing this, the support of this bill is up about 10 percent just overnight,” Senate Majority Leader Harry Reid (D-Nev.) said Monday.

“When people see what is in this bill and when people see what it does, they will come around,” said Sen. Chuck Schumer (D-N.Y.), a key negotiator on the bill who helmed the Democrats’ campaign committee for two cycles. “The reason people are negative is not the substance of the bill but the fears that the opponents have laid out. When those fears don’t materialize, and people see the good in the bill, the numbers are going to go up.”

Perhaps, but Reid, Schumer and their colleagues still face a daunting task. Just look at the numbers: According to the most recent NBC/Wall Street Journal poll, 47 percent of voters oppose the party’s health care plan, compared with 32 percent who support it. The Pew Research Center puts the spread at 35 percent for, 48 percent against. And the most recent ABC News/Washington Post poll showed a precipitous drop in support for the overhaul in just the past month.

In Arkansas, where Democratic Sen. Blanche Lincoln faces a tough reelection fight, voters overwhelmingly oppose the party’s health care push, 65 percent to 32 percent, according to Rasmussen. The same holds true in Louisiana, where Democratic Sen. Mary Landrieu gave President Barack Obama critical support for the bill. Landrieu has a few years before she runs for reelection, but the sagging polls made it harder for Obama and Reid to earn her support. And if the polls are right, voters in Nevada don’t exactly appreciate Reid’s efforts to push the president’s top legislative priority across the finish line. His 39 percent approval rating mirrors the level of support for the health care bill back home, according to another Rasmussen poll conducted this week.

The public push for health care has ensnared even some Democrats who were once thought to be safe. In North Dakota, veteran Sen. Byron Dorgan might have a race on his hands if the Republican governor, John Hoeven, decides to launch a bid. And Dorgan’s support for health care probably won’t be a big selling point; according to a Rasmussen poll released Monday, twice as many likely voters oppose the health care push as support it, 64 percent to 30 percent.

The unpopularity of the issue has also caused headaches for the state’s lone House member, Democrat Earl Pomeroy, who has already run television ads in local media markets to insulate himself from a barrage of special-interest attacks back home.

Republicans and outside interest groups who opposed the Democrats’ health care push have spent millions of dollars and thousands of hours blasting the effort. In the past few weeks, Senate Republican leader Mitch McConnell has regularly cited the negative poll numbers in his comments on the chamber floor and in daily press briefings.

The shifting nature of the legislation has made it harder for Democrats to defend the bill.

“You really need to have these things in there for a long time before voters know what they are,” Blendon said.

Yet there is conflicting evidence about whether more knowledge will help the Democrats’ cause. The poll numbers were highest in June, before Congress started considering actual bills. Those numbers dipped in July, as a trio of House committees approved components of a unified bill; and the real slide occurred in August, when lawmakers were confronted by their constituents in angry town hall after angry town hall. Democrats got a big bump in September after Obama’s speech to a joint session of Congress, but the approval ratings have been declining ever since.

Clearly, fears about the economy have played into people’s fears about what Democrats are trying to do to the health care system, even as a Congressional Budget Office assessment that the bill will cut the deficit over the next decade seemed to make little dent in the conviction that the bill will be a budget buster.

“There’s more skepticism about health care because of the economic situation,” Blendon said. “Because of existing deficit concerns, people are skeptical of the CBO claims.”

What’s more, during Obama’s tenure in the White House, voters have become more conservative, according to a recent assessment from Pew.

“What’s really exceptional at this stage of Obama’s presidency is the extent to which the public has moved in a conservative direction on a range of issues,” wrote Andrew Kohut, president of the Pew Research Center. “These trends have emanated as much from the middle of the electorate as from the highly energized conservative right. Even more notable, however, is the extent to which liberals appear to be dozing as the country has shifted on both economic and social issues.”

The goal for Democrats now is to excite those in their base by convincing them that a much-scaled-down health care bill will still make radical changes to the current system.

“They’ll have to convince Democrats that there’s a huge price to failure,” Blendon said.